Graphitic Grain-Network Nanoarchitecture for Ultrahigh-Rate and Exceptionally Durable Potassium Ternary Intercalation

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Potassium-ternary graphite intercalation compounds (K⁺-T-GICs) show promise for high-power potassium-ion storage.
• Their practical use is hindered by low reversible capacity and poorly understood electrolyte-dependent behavior, linked to salt-induced decomposition.

Purpose of the Study:

• To investigate the electrolyte decomposition mechanisms affecting K⁺-T-GICs.
• To engineer a novel electrode architecture that enhances performance and stability.

Main Methods:

• Analysis of salt-dependent electrolyte decomposition and its impact on ion transport and structural integrity.
• Design and synthesis of a disordered grain-network graphitic nanosheet (DGN-GNS) architecture.
• Electrochemical characterization of the DGN-GNS electrode for capacity, rate capability, and cycling stability.

Main Results:

• Electrolyte decomposition products were identified as the cause of resistance growth, blocked K⁺ diffusion, and graphene exfoliation.
• The engineered DGN-GNS architecture effectively suppresses exfoliation and maintains ion transport pathways.
• The DGN-GNS electrode achieved a high reversible capacity of ~165 mA h g^-1, with sustained ~80 mA h g^-1 at 30 A g^-1 and excellent cycling stability over 10,000 cycles.

Conclusions:

• The study elucidates the critical role of electrolyte decomposition in K⁺-T-GIC performance limitations.
• The novel DGN-GNS architecture establishes a new benchmark for K⁺-T-GIC anodes, offering unprecedented high capacity, rate capability, and cycling stability.